title: Amyloid deposition in 2 feline thymomas.
abstract: Two cases of feline thymoma with amyloid deposition were encountered between 1982 and 2010. Neoplastic cells were separated by abundant, pale eosinophilic, homogeneous material that was congophilic and birefringent. Ultrastructurally, the neoplastic cells were connected by desmosomes, and the extracellular deposits were composed of nonbranching, hollow-cored fibrils, 8-10 nm in diameter. In the case with sufficient archived tissue for additional sections, the amyloid remained congophilic following potassium permanganate incubation, and the neoplastic cells were immunoreactive for pancytokeratin. The histologic, histochemical, ultrastructural, and immunohistochemical features of both neoplasms are consistent with epithelial-predominant thymoma with the unusual feature of intratumoral amyloid deposition. The affinity of the amyloid for Congo red following potassium permanganate incubation is consistent with non-AA amyloid. The ultrastructural findings were consistent with amyloid production by the neoplastic epithelial cells.
authors.affiliation: Department of Veterinary Pathology, College of Veterinary Medicine, Iowa State University, Ames, IA, USA. burrough@iastate.edu
authors.forename: E R
authors.initials: ER
authors.lastname: Burrough
authors.forename: R K
authors.initials: RK
authors.lastname: Myers
authors.forename: S J
authors.initials: SJ
authors.lastname: Hostetter
authors.forename: L E
authors.initials: LE
authors.lastname: Fox
authors.forename: B J
authors.initials: BJ
authors.lastname: Bayer
authors.forename: C L
authors.initials: CL
authors.lastname: Felz
authors.forename: K R
authors.initials: KR
authors.lastname: Waller
authors.forename: E M
authors.initials: EM
authors.lastname: Whitley
mesh_terms: D000682:Amyloid / Q000378:metabolism*; D000818:Animals; D002371:Cat Diseases / Q000378:metabolism / Q000473:pathology*; D002415:Cats; D005260:Female; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008297:Male; D008479:Mediastinal Neoplasms / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D011241:Prednisone / Q000627:therapeutic use; D012189:Retrospective Studies; D013945:Thymoma / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*
chemical_list: D000682:Amyloid; D007166:Immunosuppressive Agents; D011241:Prednisone